The present invention relates to a conveying system having a plurality of work platens or tables movable through successive work stations and more particularly to vacuum means for holding the work in position on the platens both in the work stations and between work stations. The invention most particularly relates to an indexed multicolor screen printer line having a work station for each color.
It is known in the screen printing art that endless conveyor means containing a plurality of work platforms or platens can be used to move the print substrate on the platens through the various screen printing stations. It is also known that the substrate to be printed can be held on the platens by a vacuum. However, problems are encountered in holding the substrate in an absolutely fixed position on the platen not only while the platens are stationary in each of the printing stations but also while the platens are in motion between stations. One solution found in the prior art is for each platen to have its own vacuum system.
However, these systems are expensive and complicated.
Another problem is that such multicolor printers have a fixed configuration with a fixed number of printing stations printing a fixed number of colors. If additional colors are to be printed, the work must be run again through the same or a different printer having the additional colors. This greatly limits productivity.